feat: economy system with minigames, bank, rob, jobs, fishing, blackjack, slots
+ economy domain (EconomyAccount, Job, SlotCombination, EconomyTransaction)
+ EconomyRepository + SqlEconomyRepository + DB schema
+ EconomyService (transfer, daily, deposit/withdraw, stat upgrades)
+ FishingService (fish grid with difficulty levels, speed bonus)
+ BlackjackService (dealer stands on 16, ties lose)
+ SlotService (weighted combos up to x50)
+ JobService (6 jobs with level reqs and efficiency stat)
+ 11 commands: balance, baltop, pay, daily, bank, rob,
fish, blackjack, slot, job, work
+ Tests for SqlEconomyRepository
+ EconomyModule + EconomyCommandRegistrar wired into BotModule